Material



March 12, 1929. |RV|NG 1,705,015

ROOFI NG MATERIAL Filed Nov. 22, 1922 FIEIA.

/3 IN V EN TOR.

14.11. Irv/1 5;, ATTORNEYS.

Patented Mar. 12, 1929. I

narrso srarss rarest orrica.

ANDREW H. IRVING, OF BERKELEY, CALIFORNIA, ASSIGNOR TO THE PARAFFINECOMPANIES, INC., OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF DELA-WARE.

ROOFING MATERIAL.

Application filed November 22, 1922. Serial No. 602,540.

My invention relates to roofs and roofing material and especially to asheet roofing ma terial largely bituminous in nature of special value ontanks or reservoirs for pet-roleum oils.

One of the objects of the'i'nvention is the provision of a. felt baseroofing material having a high degree of resistance to the attacks ofthe fumes or vapors rising from below.

Another object of the invention is the provision of a roof of thecharacter described which is low in cost, possesses a high standard ofdurability, and which is capable of the same Wide variety of surfacetreatment or finish possessed by the general classof bituminous, feltroofings.

My invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of my invention. It is to be understood that Ido not limitmyself to the showing made by the said description as I may adoptvariant forms of my invention within the scope of the claims.

Referring to the drawings: Fig. 1 is a vertical section taken thru aportion of the'outer element of my roofing structure. Fig. 2 is asimilar section thru the inner element. Fig. 3 is a vertical sectiontaken thru a portion of roofing in which the two element-s shown inFigs. 1 and 2 are combined. Fig. 4C is a perspective view of a portionof a roof laid in accordance with my invention, the near edge being insection.

The figures of the drawing are not drawn to scale, but certain portionsthereof are exaggerated in order to show the structure more clearly.

A roof in accordance with myinvention will find wide application in oilfields, pipe line stations, petroleum refineries and in other localitieswhere storage tanks or reservoirs for petroleum oils are used; also inestablishments where volatile petroleum solvents are used forextraction, Washing and in other Ways. Not only is the roofing of myinvention low in cost, but it is easy to apply, very durable in respectof weather wear and, as its dominant quality ishighly resist-ant toattacks by the oil fumes or other vapors Which form Within the tank orother inclosure covered by the roof.

Bituminous felt roofings have heretofore been applied to the usesreferred to, but with rather unsatisfactory results. Oil vapors arisingfrom the oil in the reservoirs collect under the roof structure andeffect highly in jurious changes in the covering material, which appearsto absorb the vapors largely for the reason that the asphalt containedin the roofing is closely akin to the vapors themselves. Probably thephenomenon of condensation plays an important part in the vapor attackas the oil in the reservoir is often warm, whereas the roofing may bechilled due to weather conditions. however, the results appear to be thesame in all cases. The roofing changes from a firm, dense sheet ofsaturated and coated felt into a pulp-like mass of felted fibers whichrapidly dries out with loss of considerable asphalt. Weather actionstill further disintegrates the injured fabric, until finallydestruction of the roofing occurs at the point of attack, and with thesweeping away of the destroyed material by wind and rain, a holeappears.

My roofing material is prepared by saturating a roofing felt with asemisolid bituminous compound, giving to the saturated felt a coating,designed to resist weather action, and applying to the back of thesheeta backing composed of a material which is not easily dissolved by anddoes not readily absorb petroleum fumes or vapors. By the termdissolved, I means the absorption or condensation of the vapors on or inthe backing compound.

Suitable materials for the backing compound cover a wide range. Some ofthese are bituminous and some are nonbituminous in character. Among themmay be mentioned inontan wax, shellac, rubber, stearin pitchparticularly when oxidized by exposure to the air, the dried film oflinseed and similar varnish oil, and various forms of nitro-cellulose.Particular mention is made of coal tar pitch, especially a pitch havinga high percentage of free carbon. Such pitches are not easily attackedby petroleum vapors, although they will absorb to a certain degree thevapor of benzol or toluol to which they are more closely akin.

It will be understood that the material selected for the back of theroofing to give it resistance to oil fumes must form a durablecontinuous film over the back of the satu- Regardless of theory,

rated roofing felt and must make a good and permanent bond therewith.Silicate of soda falls within the class of ma rials which will not bereadily dissolved by condensed or absorbed oil vapors, and silicate ofsoda may be applied in the f ,rm of a water-glass in a film-like form tothe back of a shoot of asphalt or bituminous saturated felt, but it willnot form a permanent coverage because it will contract, pull apart andpull away from the felt 1- Wing an open road for the invasion ofattacking oil vapors. Home of the matcrials mentioned cannot be madereadily to adhere to an aspha t saturated felt surface, such forinstance as rubber, but if vulcanized rubber be finely divided, as by abuffing wheel, and then mixed by means of heavyrollers with a small.proportion of pine tar and sulphur and then sheetod onto the asphaltsaturated sheet and cured under an elevated temperature, all of whichoperations are easily comprehended. to those skilled in the manipulationand working of rubber, a backing for the roofing within the meaning andpurpose of this invention is secured.

Linseed oil is readily soluble in petroleum oils. It cannot be appliedto an asphz-ilt saturated felt sheet and dried as it might be applied toa sheet of metal and dried to a condition in which it resists dissolvingpetroleum oils. However, a heavily bodied linseed oil in which strongdricrs are incorporated, may be made to dry, particularly if mixed witha material such as certain stearin pitches, that is stearin pitcheswhich skin over readily. A combination of such a stoarin pitch andheavily bodied linseed oil of quick drying properties can be applied tothe back of roofing material and will be permanently impervious to oilvapors or fumes within the extent deemed practicable for this invention.

Minerallillers may be added to any of the materials which may be chosenfor the oil resistant backing, and such a filler may be very desirablewhere price is a consideration. Generally speaking, however, the use ofsuch mineral fillers in a large proportion tends to form avenuesthru'which the vapors or condensed oil may find a way to the asphalt orbitumen in the felt and this, of course, impairs the durability of theproduct.

, As the application of a single coating of an oil resistant backing mayproductive of pinholes thru which the destructive vapor may find accessto the bituminous saturation of the felt and the other easii destroyedportions of the roofing, it may be advisable at times to apply twocoatings of the oil resistant backing. These tw coatings may bedifferent in nature, that is, the first coat may be a shellac coatingand the second, a coating of linseed oil which is subsequently dried andwhich may contain so icien t mineral fillers to materially reduce thewell known contractive nature of the linseed oil film which oftentimescauses it to pull away from a satrated roofing felt sheet. Theapplication of two coats brings about the'covering of the pinholes inthe first coat by the second coat.

For the general run of work it is advisable not to concentrate theefforts on making the backing of the roofing perfectly oil-proof, but togive ita degree of oil-proofness con sistent with the cost ofmanufacture which necessarily forms a more or loss rigid limitation on.the labor and the materials which go to make the complete roofing sheet,and then give attention to the problem of lessening the amount of oilvapor which reaches the resistant under side of the roofing sheet.

In order to prevent the oil vapors from reaching the roofing, except ina diminished volume, various't xmes of dense paper sheets are used.These are durable when laid underneatha roofing of the kind hereindescribed and they hold back the amount of oil vapor which normallywould pass at the place they are laid. WVhile this invention does notcontemplate a restriction to any one type or grade of paper, save thatit gives preference to hard, strong, closely formed sheets, yet forpractical purposes it is found thata good grade of paper known as rosinsized sheathing will give satisfactory results. Preferably the gradeweighing fort-y pounds per roll, that is to say forty pounds per fivehundred square feet, is used and this should preferably be well sizedand calendered till it is dense and hard. One or more layers of suchsheathing paper may be used beneath the roofing. They may be nailed downor otherwise secured as by cementing over a portion or all of the areawith coal tar pitch. Two or more layers may be joined together bycementing the layers to each other with silicate of soda, or by coal tarpitch, or any other of the chosen oil-proof or oil-resistant materialswhich will exert a cementing action. If but one one layer of thesheathing paper is to be used, it is advisable that the lap jointsbetween adjacent sheets be cemented with silicate of soda. In someinstances it is found advisable to give to the sheathing paper a coatingof the same sort as that used for the backing of the roofing felt. Thisrenders the paper still more impervious to the oil vapors.

If desired, the sheathing may be coated on both sides, or two layers ofsheathing, either or both being provided with the coating of oilresistant material, may be used.

The above contemplates the use of two roofing elements appliedseparately to form the complete roof. I may in some instances and forsome uses prefer to use a single element, that is, to unite the twoelements of felt and paper at the factory. It is obvious that at thefactory, but may comprise an adhesive coat applied over the laid papersheathing immediately prior to laying the saturated felt.

It will be apparentfrom theforegoing that a wide variety of combinationsis possible with the. different elements of this invention adapting itto a wide range of conditions regards severity of exposure, and allowinga wide range of cost according to the completeness with which protectionagainst vapor attack is carried out.

Referring now to the drawings which illustrate the preferred embodimentof my invention, a sheet of felt 2, of the kind used for making roofingsheets is saturated with a semisolid bituminous material, preferablyasphalt having a softening point of approximately 100 F, and apenetration of about 180 11, by the methods of the American Society forTesting Materials, standard for 1921. The saturated felt is coated withan asphaltic coating 8, which may be finished with soapstone or flakegranules or other mineral matter in accordance with prevailing practicesin the roofing industry. On the opposite side of the saturated feltsheet is a backing l, of coal tar pitch, preferably one having apercentage of free carbon, as determined by the difference between thenon-soluble in redistilled benzol and the incombustible matter of 30 percent and havinga softoning point of 17 0 F. by the method of theAmerican Society for Testing Materials, Serial D 6120.

In Fig. 2 is shown a sectional view of a piece of paper 6, such as isused for the sheathing, and to which a coating 7. of coal tar pitch ofthe same characteristics as above described, is applied by rollers orscrapers in a manner well known to manufactures of such coated papers.Preferably the coating amounts to about three pounds per hundred squarefeet of paper.

In Fig. 3, I have shown a sectional view of a complete roofing in whichthe )aper sheathing 6 is applied to the heated or semi-molten backing aof the fel 2, so that such backing adhesively unites the felt and paperinto one composite sheet. This of course is done during the course ofmanufacturing the roofing and under factory conditions.

In Fig. 4 is shown a complete roof comprising the sheathing 67 of thecharacter shown in Fig. 2, and nailed to a roof decking 8, by means ofnails 9. The lap between the sheets of sheathingis filled with anadhesive paint 12, made by heating a coal tar pitch of the characteralready described and, while in a melted and warm condition, dissolvingit in benzol.

It is preferred to lay this sheathing with the coated side upwardbecause it interposes the thickness of the sheathing between the oilvapors and the first layer of coal tar pitch. It is found that coal tarpitch is resistant to oil be free to drop away from the paper and thusopen an avenue for the vapor to pass into and thru the-paper to a muchgreater degree.

Grer the sheathing layer is a sheet of the doubly coated roofingmater'al shown in Fig.

1, with the oil resistant backing or coating next to the sheathinglayer. Adjacent sheets are connected by lap joints secured by nails 13,.in the manner usually followed in applying felt base roofing. The lap ismade weather-tight by a cement paint 14:, which ced not necessarily haveoil resistant properties.

From the above it will be clear that my roofing provides the sameexcellent wearing surface as to weather conditions that is found inordinary felt base roofing coated and surfaced described, and inaddition such felt protected from the attack of vapors from below by thecompacted paper sheet and two separate layers of coal tar pitch. It isquite obvious that under these conditions the saturated felt sheet whichcomprises the main portion of the roofing, is substantially free fromthe attack of oil vapors, and under difficult conditions shows adurability and useful life comparable to that of felt base roofings ofsimilar grade under ordinary conditions of application.

I claim:

1. A roofing comprising an outer layer of felt saturated with bituminousmaterial and coated on the under side with a material resistant to theattack of a vapor deleterious to said bituminous material, and anunderlying sheathing of compacted rosin sized paper.

2. A roofing comprising an outer layer of felt saturated with bituminousmaterial and coated on the under side with a material resistant to theattack of a vapor deleterious to said bituminous material, and capableof forming a permanent bond with said bituminous material, and anunderlying sheathing of rosin sized paper.

3. A roofing comprising an outer layer of felt saturated with asphaltand faced on the upper side with a cea' 'ng of asphalt and on the lowerside with a coating of coal tar pitch, and an underlying layer of rosinsized paper faced on the upper side with coal tar pitch.

l. A roofing for oil tank comprising an outer layer of felt saturatedwith bituminous material and coated on the under side with a materialresistant to oil vapor, and an underlying layer of paper coated on theupper side with said resistant material.

'5, A. rooting comprising an outer layer of fibrous material saturatedwith a Weathercompound and faced on the lower 3; of coal tar pitch, andan no layer of compacted fibrous maul with resin and faced on the upperside with coal tar pitch.

5. A rooting comprising an overlying layeroit fibrous material saturatedwith bituminous material and coated on the under side With a materialresistant to the attack of a vapor deleterious to said bituminousmaterial, and an underlying sheathing of fibrous material sized With aresinous substance.

7. A roofing material adapted to form oil tank covers comprising anouter layer of fibrous material saturated with bituminous material andfaced on the lower side with coal tar pitch and an underlying sheathingof paper.

8. A roofing material adapted to form oil tank covers comprising anoverlying layer of fibrous material saturated with bituminous materialand coated on the under side with a material resistant to the attack ofvapor deleterious to said bituminous material, and an underlyingsheathing of compact fibrous material.

In testimony whereof, I have hereunto set my hand.

ANDREW H. IRVING.

